Conventionally, there have been variously proposed tape printers and tape creating methods which performs printing on a long tape by means of a print head while conveying the long tape with a tape conveyance mechanism which is driven by a DC motor.
For instance, Japanese Patent Application laid-open No. H6(1994)-155809 (paragraphs[0008] to [0021], and FIGS. 2 to 5) discloses a tape printer comprising a print head for printing dot-pattern data on a printing medium, a conveyance mechanism for conveying the printing medium relative to the print head, and control means for controlling the print head and the driving mechanism. The tape printer further comprises a DC motor for driving the conveyance mechanism, and rotating at a constant rotational speed, without detecting a rotation angle. Printing is inhibited while the rotational speed of the DC motor is not constant immediately after the DC motor starts rotating. After the rotational speed of the DC motor becomes constant, printing is performed at a stable frequency.
As described above, the DC motor which is inexpensive and has a good energy efficiency characteristic can be employed to the drive motor of the conveyance mechanism for conveying the printing medium relative to the print head, thus a low-cost dot printer of which power consumption is low.
The tape printer comprising the conventional structures as above, however, is arranged to previously determine the rotational speed of the DC motor by resistance values of a variable resistance and a control IC. When a wire-wound resistance value increases because of the heat generation of the DC motor under the continuous driving, the rotational speed of the DC motor changes, thereby getting difficult to provide fixed-length printing with high precision. The rotational speed of the DC motor also changes due to the load change depending on the tape type.
To solve the above problems, the printing operation can be performed with the thermal head at every predetermined number of rotations of the DC motor while an encoder detects the rotational speed of the DC motor. However this causes another problem that a user cannot modify a conveyance length of the tape in accordance with the predetermined rotational speed of the DC motor. Thus, a conveyance length correction to adjust the print length cannot be performed.